Strain enhanced anisotropy of in-plane resistivity of YBa2Cu3O7-delta films

Highly bi-axially stressed, thin epitaxial films of YBa2Cu3O7-delta were deposited on mismatched, orthorhombic (001) YAlO3 substrates. Strain may be used to enhance anisotropy and affect spin and charge ordering in cuprate superconductors. The resistivity was anisotropic along the a and b axes and the ratio rho(a)/rho(b) approximate to 2 agreed well with that for untwinned single crystals. rho(a)(T), but not rho(b)(T), peaked sharply at a temperature closely above the superconducting transition temperature, while the latter estimated from rho(b)(T) exceeded the one determined from rho(a)(T). The height of the peak Delta rho(a) in rho(a)(T) decreased with increased bias current and applied magnetic field. The behavior may be explained by partly relaxed regions, preferably aligned along the b axis, but may also depend upon spin/charge ordering